We build a multicenter study whose main objective is to demonstrate the concordance of INR measurement by the capillary way (INRatio2 ®, SAS ALERE, Jouy-en-Josas) with venous technical reference. It concerns patients older than 75 years treated with VKA and hospitalized in Internal Medicine, Geriatrics and Vascular Medicine in the fours university hospital of the G4 region. The secondary objectives are to estimate the prevalence of antiphospholipid antibodies (ranging from 12 to 55% depending on the study) and their influence on the measurement of the INR by capillary method and the variability of the INR veinous measurement in function of the hospital, with a centralized INR measurement which allow to compare. 150 patients is required to perform this study.